The present invention relates to crop-harvesting implements having a mid-mounted tongue which extends over a header of the implement and, more particularly relates to such implements as are adapted for being placed on a trailer for endwise transport using the implement tongue as the towing connection with the prime mover.
The headers of crop-harvesting implements often have a working width which is too great for permitting the implement to pass through gates in fences or to be safely moved down a road. It is known to provide trailers for the endwise transport of such implements. In the case where the implement are provided with mid-mounted pivot tongues which extend over the header to the main frame of the implement, the tongues remain coupled to the tractor when the implement is loaded for transport and are used to tow the combined implement and trailer.
During normal operation of an implement equipped with a mid-mounted tongue, as described in the previous paragraph, an extensible and retractable hydraulic actuator is used to change the angle between the tongue and the implement frame so as to cause the implement to track to one side or the other of the towing tractor, this operation being desired so that crop to be harvested is not run over by the tractor. Because the implement would be unstable if the tongue were swung beyond a working range necessary for producing the above-noted tracking, it is desired to limit swinging movement of the tongue to such working range. However, it is necessary that the tongue be swung a considerable amount beyond its working range when the tongue is being used for pulling the combined implement and trailer when the implement is loaded on the trailer for endwise transport and, accordingly, it is desired to permit the tongue to be selectively swung beyond its working range to a transport position.
U.S. Pat. No. 4,558,560 discloses a stop plate carrying abutments and being mounted for selective movement between a first position, wherein the abutments are disposed for limiting pivotal movement of an implement tongue to a working range, and a second position wherein the abutments are moved to permit the tongue to swing beyond its working range to a transport position.
While the patented plate structure performs the desired function of permitting pivotal movement of the tongue beyond its working range only when it is desired that the tongue be placed in a transport position, this structure involves several parts and weldments that add cost to the implement.